Error When Assigning A GameObject To Variable Inside A Class

When i to perform this operation:

static var Player : PlayerVariables;
class PlayerVariables
  var PlayerObj : GameObject;
  Player.PlayerObj = GameObject.Find("Player"); // there is a object in the scene called Player

i get a NullReferenceException: Object reference not set to an instance of an object

what am i doing wrong?

Object is a class. Use another name (and this is one reason variables should always be lowercase).